The invention relates to a method for controlling an automatic shut-off process and/or an automatic start-up process of an internal combustion engine in a motor vehicle.
In order to reduce fuel consumption and pollutant emissions, the current trend is to develop methods and systems (and to some extent they have also been already installed) that automatically switch-off the internal combustion engine of a motor vehicle under certain conditions and/or in the presence of predetermined shut-off conditions and automatically re-start the internal combustion engine in the presence of predetermined start-up conditions. Such methods and systems, or rather such start/stop devices, are suited, above all, for urban traffic, in order to reduce the consumption of fuel, because in urban traffic the vehicle often comes to a standstill at traffic lights or owing to the traffic and because it is not necessary to run the internal combustion engine.
DE 101 61 343 A1 discloses an automatic stop and start-up control device for an internal combustion engine. In this case, the control device implements corresponding measures for shutting-off the internal combustion engine, when all of the shut-off conditions are met. For example, the speed of the vehicle has to be below a predetermined limit value. In the case of manual transmissions no gear may be engaged, and in the case of vehicles with automatic transmissions the gear shift position of the transmission must be in a neutral position.
Furthermore, DE 100 30 290 A1 also discloses a method and a system for automatically shutting-off and starting-up again an internal combustion engine. In this case, an automatic shut-off process is inhibited, when the charge state of the battery of the vehicle is below a predetermined lockout threshold. As additional shut-off conditions, it is also checked whether the speed of the vehicle is below a predetermined limit value, whether the transmission is in the idling position and whether the accelerator pedal is in the rest position.
DE 102 11 461 C1 discloses a method for automatically shutting-off and starting-up an internal combustion engine. In this case, a plurality of variables that influence the evaluation of the shut-off conditions and/or the start-up conditions are considered. Hence, it is possible to automatically shut-off the internal combustion engine, when at the same time the following shut-off conditions are satisfied:                a) the engine hood must be closed;        b) the speed of the motor vehicle is less than a predetermined speed threshold or is equal to zero;        c) the accelerator pedal is not actuated;        d) the brake element is actuated;        e) at least the driver's door is closed;        f) in the case of an automatic transmission, the selector lever is in a driving position;        g) the temperature of the exhaust gas system has reached its operating value;        h) the internal combustion engine has reached its operating temperature;        i) the transmission or transmission oil has reached its operating temperature, and, thus, even in the event that the engine is shut off, the pressure supply, and, therefore, the ability to engage the transmission and the avoidance of overheating in the transmission is guaranteed;        j) the air conditioning control unit of an air conditioning system produces an enable signal;        k) an enable signal is produced by a battery control device;        l) an optionally provided delay time has expired prior to the activation of the automatic shut-off process; and        m) an ON/OFF switch for manually switching on and off the start/stop device is in the ON state.        
However, in addition to these shut-off conditions, which are known in the prior art, yet other influential variables have to be taken into consideration so that a start/stop device of this type will be accepted by the driver and so that no implausible states will occur.
Therefore, the object of the invention is to provide an improved method for controlling an automatic shut-off process and/or start-up process of an internal combustion engine having a start/stop device.
This and other objects are achieved by a method for controlling an automatic shut-off process and/or an automatic start-up process of an internal combustion engine in a motor vehicle having of a start/stop device, by which, following a start-up of the internal combustion engine by a person and after driving the motor vehicle, the internal combustion engine is automatically shut-off upon stopping the motor vehicle, when predetermined shut-off conditions are satisfied by corresponding influential variables, and/or by which an automatically shut-off internal combustion engine is automatically started, when predetermined start-up conditions are satisfied by corresponding influential variables. At least one of the following variables influencing the evaluation of the shut-off conditions and/or the start-up conditions is taken into consideration:                a) a presence or absence of at least one of a driver identification transmitter and a vehicle key;        b) a current state of a tank ventilation system;        c) a current tank fill level of a fuel tank;        d) a current state of a diesel particulate filter present in the vehicle;        e) an activity state of at least one of a workshop mode, a works mode, a service mode, and a production mode;        f) a current ambient temperature outside the vehicle;        g) an evaluation of a device for detecting occupancy of the driver's seat wherein the device for detecting occupancy of the seat is configured as at least one of a seat occupancy mat, a camera system, and a seat belt buckle evaluation system;        h) a detection of a cylinder synchronization process;        i) an activity state of a driving speed control system;        j) an activity state of an auto hold function in the motor vehicles having an automatic transmission;        k) an activity state of an electric parking brake; and        l) an activity state of a hill hold function.        
In addition to the known variables that influence the control device of an automatic shut-off and/or start-up process by means of a start/stop device, a plethora of other influential variables must also be taken into consideration in accordance with an embodiment of the invention so that a start/stop device offered to the customer and intended for automatically shutting-off and starting-up the internal combustion engine experiences the highest possible acceptance by consumers and so that no implausible system or vehicle states occur.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawing.